"Humiliatingly hawking himself for the Speaker's job to his political enemies because his own party wouldn't support him. When you started life as a working class hero and morph into someone who publicly offered to sweep the floor for Don Brash, there's nothing else to say. Referred to these days as Uncle Tau. Sad and embarrassing," Mr McCarten wrote.

Mr Henare, who is chairman of the Maori Affairs Committee, this morning tweeted about being called Uncle Tau, "like me calling him [Matt McCarten] that back in the 80s 4 not s'portng Maori unionists," he tweeted.

This prompted Mr Henare to respond: "yeah you would know I spose, how many schools did you close? Maori ones too. Ah well. We all can't be saints".

St Stephen's - a Maori boarding school - was closed in 2000, after Mr Mallard announced the Labour government would cut funding.

Mr Mallard, who was Education Minister at the time, responded that Maori schools closed because middle-class urban Maori chose not to send their children to them.

Mr Henare, who was Maori Affairs Minister from 1996 to 1999 and Associate Education Minister from 1998 to 1999, said he introduced a scholarship programme to send rural Maori to top schools, but Mr Mallard closed that down too.

He then said Mr Mallard blamed Maori for the closure of St Stephen's.

"...hard to reopen without support from leading whanau willing to send there kids there and they aren't".

Earlier this month Mr Henare gave up on his ambition of becoming the Speaker next year after the Maori Party pulled its support for him.